1. Field of the Invention
The present invention relates to the supply of idle bypass air and exhaust gas to the intake manifold of an internal combustion engine and, more particularly, to an integrated idle air and exhaust gas recirculation supply system having a control valve assembly for control of both idle air and exhaust gas.
2. Description of the Relevant Art
Typical automotive internal combustion engines utilize an idle air bypass system for the control or stabilization of engine speed during idle operation. Such a system may have an electrically operated valve assembly which modulates the air passing through a conduit which bridges the throttle plate of the air intake to the engine. The valve assembly may be controlled by the engine control module or other suitable controller which is capable of monitoring predetermined engine parameters which are affected by load changes requiring a change in engine speed.
In addition to the idle air bypass system, the advent of various emission control schemes for meeting regulatory requirements has necessitated the use of recirculated exhaust gas for controlling temperatures in the combustion chamber of the engine. The control of exhaust gas quantities fed to the engine intake may be achieved through the use of an electrically operated exhaust gas recirculation (EGR) valve which is controlled by the engine control module or other suitable controller capable of responding to information regarding various predetermined engine parameters received from sensors disposed throughout the engine, intake and exhaust systems of the engine.
In most cases, idle air and EGR operate exclusive of one another. That is, idle air and EGR rarely are required to be supplied to the engine at the same time since EGR is operational at off-idle throttle position and idle air control (IAC) is functional primarily during idle operation.